A bit warmer weather has meant it’s been possible to be working in the workshop again, so hot on the heals of the new lantern pinions yesterday comes a new bush for the fly arbour.
Rather than making it out of phosphor bronze, as you might normally for a bush, it’s machined out of brass. This is primarily because we didn’t have any phosphor bronze of sufficient size and it’s much more expensive to buy than brass. It’s a fairly substantial bush and the forces through it shouldn’t be too high (there is no force pushing the arbour against the wall of the bush, except for a little gravity), so it should be fine. If we’re wrong it’s not the end of the world, it’ll just have to be replaced when it wears.
The bush is a tight push fit into the arbour support pillar and was pressed in with a vice. Next it needs to be reamed out, using a reamer mounted on an arbour passing through the bush on the opposite pillar, to ensure perfect alignment.